Did it! I succesfully installed an Unorthodox underdrive pulley on the J. Runs great now too! Pretty cool when you notice the differences instantly although Unorthdox claims 5-6 days for your ECU to learn.You can almost follow the installation direction to the 't'. I found the directions on twinturbo.net very helpful. There's only one difference between the J and the Z apparently. The power steering pump pulley on the J is made for a belt with 3 teeth while the Z is made for 4. But whatever I made it work. There are two solutions. Either get the Unorthodox P/S pulley and use the listed Gates belts part# or just get the same size belt with 3 teeth because it'll still fit real good on the UDP w/3 or 4 teeth. The part # given for the Z is Gates K040355(belt 4PK903) the belt for the J is a 3PK903. I'm guessing that the leading number has to do with the teeth so just purchase a 3PK903 for the job.As far as the effects of underdriving I haven't noticed anything, and no one has ever noticed anything that drives a Z. At idle with all accersories on there was no dimming of lights. Unorthodox claims a 15 HP gain, and at first I thought this might be optomistic like most aftermarket products, but I think this is most likely true.Just the weight difference between the two was astounding. I haven't weighed the stock pulley yet, but it's probably 10 lbs more then the new one which weighs 3.4 lbs.

Well that just damned cool! I wish a company would step and do the same with the Q45.

NICE NICE NICE! finally! long awaited! if i was within 100 miles of my J right now, i would put one on in an instant, along with those AT italia wheels, haha. only 11 months to go!~

i got a crap load of pics i took during the install if you need some help. the worst pics but the most helpful will probably be the taking off the starter and shoving a screwdriver in the crank teeth to stop it from turning when taking off the crank pulley.

Next project: See if the Z headers work. Man they look like a pain. The J's and the Z's look very similar but the drivers side is what worries me. There's so much stuff in the way like the steering column, the passengers doesn't look that hard. That'll be a lot bigger project(more like an experiment) that could be for nothing.

the most amazing part, Stillen had the cheapest price on the pulley.

The problem with HP increases is they are at the highest rpm attainable.At 600-4000 rpm where heavy cars spend the most time and in the critical 0-30 mph acceleration UDP don't help any measurable amount.

Always important to check the imaginary dyno gains with a stopwatch to see how the acceleration curve reacts to the addition of the air resistance load.

Owners who use the AC/heater on HIGH and/or the rear window defroster with the headlights will find that the alternator can't keep up at cruise below 2400 rpms. The electrical system is barely balanced stock.

Engineers have unlimited pulley ratios to chose from, it amazes me that one would think that they intentionally chose to limit the acceleration by chosing a ratio that was not needed for something?

But they have to deliver the adequate AC, PS, cooling, charging capacity as their first order of business.

"These gains are obtained in two ways. First, and most important, is the weight loss. There is an average of 2.7 HP gained from every pound lost off the crank shaft. With the lighter accessory pulleys, as much as 15% to 30% more power can be found. 85% of our gains are from weight loss. {!!!!!!!!!!!!!!!!!!!!}

The rest of the gains are from underdriving, which accounts for about 15% of the total gains. We do not push underdriving for two main reasons. Our main reason is to keep charging systems, air conditioning, power steering, and water pumps moving fast enough for every day driving. Second, not much horsepower is gained from extreme underdriving."

What they don't tell you is the crankshaft pulley weight is part of the engine balance equation so less weight will mean a rougher less balanced engine ....important for longevity ....if that matters.

On a Q the crank pulley damper was made extra heavy to help reduce vibrations and the exact weight is needed to properly load the front crank bearing!!!!!!!!!!!!!!!!!!

Remember ever engine can double the generated HP the question is how many hours [minutes] it will last?

well, i rarely use the a/c and never use the rear defroster and using the two together probably means the end of the world is coming anyway. but yes, unfortunately with every modification there's a downside and more then likely it's always longetivity of your motor. oh well...toys!

Q45tech wrote:What they don't tell you is the crankshaft pulley weight is part of the engine balance equation so less weight will mean a rougher less balanced engine ....important for longevity ....if that matters.

On a Q the crank pulley damper was made extra heavy to help reduce vibrations and the exact weight is needed to properly load the front crank bearing!!!!!!!!!!!!!!!!!!

People who use undampened crank pulleys on mkiv Supras have had problems with bolts coming loose on the front of the motor, flex plate bolts coming loose on cars with auto trannies etc. Not worth the minimal gain in power IMO. That damper is there for a reason.

EWT wrote:People who use undampened crank pulleys on mkiv Supras have had problems with bolts coming loose on the front of the motor, flex plate bolts coming loose on cars with auto trannies etc. Not worth the minimal gain in power IMO. That damper is there for a reason.

trust me, i did the research for the pulley on this motor. i couldn't find one example of where it screwed someone up. if problems were common and we all know problems easily show themselves on the internet i would have reconsidered, but no probs were found so i trucked on ahead! woohoo. free bird dawg!

Mayhem_J30 wrote:trust me, i did the research for the pulley on this motor. i couldn't find one example of where it screwed someone up. if problems were common and we all know problems easily show themselves on the internet i would have reconsidered, but no probs were found so i trucked on ahead! woohoo. free bird dawg!

Go search the archives from the mkiv supra list on yahoo groups. You'll find quite a bit of discussion about them.

EWT wrote:Go search the archives from the mkiv supra list on yahoo groups. You'll find quite a bit of discussion about them.

well supra's might have had problems but apparently the Z's have not. good motors eh? nissans rock :ylsuper

Mayhem_J30 wrote:well supra's might have had problems but apparently the Z's have not. good motors eh? nissans rock :ylsuper

Torsional vibration (which is what the damper dampens) is present in any motor whether it's a Toyota or Nissan. http://www.dinanbmw.com/html/d...s.htm has a good explanation of what happens. However, I'd guess it is more of an issue with an I6 than a V6 due to the length of the crank. In any case, I hope you're not implying that the motor in the Z is stronger than the one in the Supra

EWT wrote:Torsional vibration (which is what the damper dampens) is present in any motor whether it's a Toyota or Nissan. http://www.dinanbmw.com/html/d...s.htm has a good explanation of what happens. However, I'd guess it is more of an issue with an I6 than a V6 due to the length of the crank. In any case, I hope you're not implying that the motor in the Z is stronger than the one in the Supra

depends on what you mean by stronger. nah, i love supra's.turbos are good ummmkay.but like you said, they are two totally different motors and they respond differently to different things. later

the vg series of engines tend to work well without the harmonic balancer .. But just as changing the flywheel lightens weight on one end, an UD pulley throws the balance of any engine slightly out of whack. it just so happens that as long as the vg series engine doesnt have significant bearing wear, the life of the engine will most likely remain unchanged. other makes (mitsu, toyota) are notorious for the opposite, where they often are stricken with a "walking crank." mention those words to any knowledgeable dsm or toyota driver, and they quiver at the thought of what their UD pulley is doing to their engine. mention it to a vg nissan series owner, and theyve never heard of it. and thats because it simply never happens (unless there was an already existing problem). maybe its the ridiculously rugged cast iron block, strengthened crank, and tightly toleranced jounals. oh, wait... that IS the difference. (although the waking crank in mitsus is simply a result of poor build quality)

HEY.. Mayhem,Stillen Motors told me that the headers from the Z would'nt fit the JAY

Eswift wrote:the vg series of engines tend to work well without the harmonic balancer .. But just as changing the flywheel lightens weight on one end, an UD pulley throws the balance of any engine slightly out of whack. it just so happens that as long as the vg series engine doesnt have significant bearing wear, the life of the engine will most likely remain unchanged.

It's not a balance issue, it's a vibration issue that the stock pulley is designed to dampen. When you take the stock pulley off, you're losing the dampner and creating extra wear on the bearings. How much extra wear is open to debate, but for the minimal horsepower you're freeing up, it's not worth finding out the hard way IMO. I'm willing to trade some durability for 20% horsepower gains, I'm not for 1% gains. In any case, the strength and build quality of the motor is not the issue here. If it's less of an issue with Nissan V6s than with other motors, I'd guess it's due to the inherent shortness of the crank in a V6 rather than some "superiority" of the motor in design or build quality.

Quote »other makes (mitsu, toyota) are notorious for the opposite, where they often are stricken with a "walking crank." mention those words to any knowledgeable dsm or toyota driver, and they quiver at the thought of what their UD pulley is doing to their engine. mention it to a vg nissan series owner, and theyve never heard of it. and thats because it simply never happens (unless there was an already existing problem). maybe its the ridiculously rugged cast iron block, strengthened crank, and tightly toleranced jounals. oh, wait... that IS the difference. (although the waking crank in mitsus is simply a result of poor build quality) [/quote]

I own a Toyota (and an Infiniti), have owned a Mitsu, and haven't spent much time "quivering." It depends on which Mitsu motor you're talking about. The 4G63 was a great motor until Mitsu screwed it up by putting in weaker rods, crank, and a poorly designed thrust bearing that causes the crank walking problems. Underdrive pulleys don't cause the problem on 93+ motors, they crankwalk with or without them. The pre-93 motors are well built and very strong. I opened mine up after 125K very hard miles(75+ autoxs, numerous track events and 200+ quarter miles), most of the factory cross hatching was still intact, and the cylinders were still within spec for roundness and taper. The drivetrains are another story, but the motors are bulletproof.

Supra motors speak for themselves. 800rwhp on a stock shortblock isn't even newsworthy anymore. The very small number of motors that have actually had crank walk problems used clutchs with extremely stiff pressure plates that put excessive loads on the thrust bearing at start up. That isn't an uncommon problem on many cars when people start using pressure plates with much higher than stock clamping loads. Nissan makes some strong motors, but there isn't a stronger stock motor made cid for cid than the one in mkiv Supras.

http://victorylibrary.com/mopar/crank-b ... r-tech.htm

Why does the Q motor have a strange vibration in the 1600-1800 rpm range? Bore 3.66"; stroke 3.256", rod length 5.8".Why does turning AC on affect the engine balance slightly?Why is 7300 rpm the limit with cast pistons

Why is the Q motor compression specified at 185 psi [sealevel] and why it reads 157 psi in Denver.

Why the effective compression ratio is only 8.9:1 vs the publish static 10.2:1.........since the intake cam is open 68 degrees after the piston starts to move back up from BDC till oil pressure rises enough to move it [intake cam] back 20 degrees reducing the charge reversion.What is effective CR at 2000 rpm cruise, at 4,000 rpm torque peak, at 6,000 rpm HP peak.http://victorylibrary.com/mopar/cam-tech-c.htm

What effect will the new 5.0 and 5.5 liter V8 motors have on ultimate reliability......

SAMURAI3 wrote:HEY.. Mayhem,Stillen Motors told me that the headers from the Z would'nt fit the JAY

did you talk to a rep or a someone important? as far as they're concerened if a rep doesn't see it in the computer they'll say it doesn't fit. Remeber the pulley 'didn't fit' either. i don't plan on finding out during the install anyway. i'm trying to get a hold of some J exhaust manifolds and compare the two for fitting. i imagine the flanges would mount right up to the J block, it's the shaping that I'm worried about getting through all the chaos packed under the hood. i also have a really good exhaust shop close by to do the piping between the manifolds and the cats. i just get bored a lot so i start doing this stuff.

I talk with one of the TECHS